It is often desirable to measure the peak-to-peak value of a time-varying analog signal. One way to measure the peak-to-peak value is to use two digital-to-analog converters (DACs) to capture the positive and negative peaks of the signal. The negative peak DAC output is subtracted from the positive signal DAC output to provide a measure of the peak-to-peak voltage of the signal.
One application for such a peak-to-peak signal detector is in magnetic field sensing circuits, such as a gear tooth sensor which provides an output signal that changes state upon the approach or retreat of each tooth of a rotating ferrous gear. In such circuits, a magnetic field-to-voltage transducer, such as a Hall effect device or magnetoresistive device, is used to generate a signal proportional to the strength of the magnetic field caused by the ferrous gear. It is sometimes desirable to measure the peak-to-peak voltage of the magnetic field signal, such as for the purpose of enabling a comparator once the peak-to-peak signal has reached a predetermined minimum value.